Evaporation of water droplets with metallic inclusions

The dynamics of non-axisymmetric evaporating droplet with metallic inclusions heated in a high-temperature gas flow are experimentally studied. The type of metallic inclusion is found to play a critical role in the transient flow dynamics and associated heat transfer. Experiments were conducted with eight metals and alloys currently used in industrial applications. High-speed recording (up to 102-104 frames per second) allowed measuring lifetimes of water droplets with different metallic inclusions (1 mm or 2 mm in size) when increasing the gas temperature from ∼300 K up to about 900 K. We propose a candidate mechanism of evaporation that explains the differences between measured droplet lifetimes in the performed tests. Furthermore, the conditions to provide the most effective cooling are determined. They are based on the balance equations taking into account warm-up times of inclusions and the ratio between the latent heat of vaporization of water, the energy used to heat up water and the metallic particles.